Module tree 

The Download scene’s model: manifest + cache → categories, levels and leaves with checkboxes. No Win32 and no display strings, so it is testable anywhere.

Modules

arena 🔒

build 🔒

cached_package 🔒

node 🔒

selection 🔒

Structs

CachedPackage

What the cache holds for one package, as the tree needs to see it.

Node

One row. Grouping rows carry no package.

Tree

Nodes in a flat arena, so a node’s index can ride in a tree view item’s lParam.

Enums

Check

A row’s checkbox; a grouping row’s is derived from the leaves under it.

LeafState

Where a leaf stands between the server and this computer.